Flying head or "Winchester" disk drives include a head-disk interface which is separated by a very thin film of air molecules. As data storage densities become higher per unit surface area, flying heights of heads above disks become lower and lower. In contemporary disk drive designs it is not uncommon to specify head to disk surface separation in a range of 1.5 to 3 microinches. Very minute particles within the head-disk chamber and having sizes greater than the flying height may destructively interfere with the head and/or storage media. Considerable attention is therefore given to removing any free particles from circulation within the enclosed head and disk assembly by filtration techniques. Air filters for inclusion within head and disk assemblies are well known in the prior art. An early example is found in U.S. Pat. No. 3,839,734. A later example is found in U.S. Pat. No. 4,369,475.
In terms of environmental particulate filtering within the very clean interior of the head and disk assembly, in prior disk drive designs, air filters were supported within and by specially provided structural features cast into the deep-dish base casting. Such cast-in filter-supporting features could be provided only by separate structural support elements which have to be added to flat, sheet metal bases, at greater expense and with added assembly time and complexity.
Since disk drive head and disk mechanisms involve round disks which are usually contained in rectangular packages or "form factors", it is not uncommon to find that one corner of the head-disk enclosure is suitably adapted for, and equipped with, an air filter. One example of this kind of arrangement is found in commonly assigned U.S. Pat. No. 4,647,997 to Westwood entitled: "Aerodynamic Latch for Disk File Actuator", the disclosure thereof being incorporated herein by reference. While the gist of this prior patent is directed to an aerodynamic latch structure for use within a 3.5 inch form factor disk drive, filter element 86 is shown placed in an upper corner of the head-disk enclosure at an opposite side of a location of the voice coil motor, and aerodynamic latch mechanism. As shown by arrows in FIG. 1 of this patent, airflow generated by disk rotation enters one end of the filter 86 and exits another end of the filter. At the same time, airflow generated from disk rotation is employed to actuate an aerodynamic actuator latch structure 46 and thereby release a rotary voice coil actuator. In the example provided by this prior patent, a base structure was formed as a "deep dish" casting, and structural features in the base were provided to aid positioning the filter element 86. Other structural features, including a vertical pin 50 press-fit into the base casting, were used e.g. to support the aerodynamic latch structure 42.
In addition to U.S. Pat. No. 4,647,997 noted above, the assignee of the present invention has pioneered the concept of an aerodynamically released actuator latch for hard disk drives. By way of example, the reader's attention is directed to commonly assigned U.S. Pat. No. 4,538,193 for "Aerodynamically Released Safety Latch for Data Transducer Assembly in Rotating Rigid Disk Data Storage Device"; U.S. Pat. No. 4,692,829 for "Magnetically Biased Aerodynamically Released Integral Safety Latch for Rigid Disk Drive"; and commonly assigned U.S. Pat. No. 5,319,511 for "Aerodynamic Actuator Latch with Magnetic Return Spring for Hard Disk Drive"; the disclosures thereof also being incorporated herein by reference.
One of the above referenced patents, U.S. Pat. No. 4,538,193, describes an embodiment of aerodynamic actuator latch including an airvane disposed beneath one of a stack of rotating disks and an air scoop portion which was located in a central portion of the latch in a vertical space between an airvane journal post and peripheral edges of the disk stack. However, in this prior approach, a separate filter element was provided in the enclosed head/disk assembly, and the air scoop was impermeable to airflow (i.e. it was not a filter element).
While the prior approaches described above worked well for their intended purposes, hitherto unsolved problems have remained. One problem has been associated with hard disk drives employing a single 3.5 inch diameter data storage disk. One prior solution proposed for this problem was to add a second, airflow generator disk, as described in the above-referenced, commonly assigned U.S. Pat. No. 4,647,997. Another proposed solution was to increase disk rotational speed to well above nominal rotational velocity during initial spin-up, in order to generate sufficient airflow to release the actuator latch, as taught in U.S. Pat. No. 5,043,834 et al. to Kubo entitled: "Actuator Locking System of Disk Unit". One other proposed solution was to add airflow generation fins to the disk spindle hub, as described in commonly assigned U.S. patent application Ser. No. 07/839,870 filed on Feb. 21, 1992 for "Airflow Generator Spindle Hub for Aerodynamically Released Disk Drive Actuator Latch".
Thus, a hitherto unsolved need has remained for air filtration support structure integrated into existing components of an aerodynamic actuator latch structure, thereby to combine the functions of air filtration and actuator latching in a cooperative, synergistic manner and to reduce overall disk drive components count and drive complexity.